docker/l3d#74 Add existing Ansible documentation

.gitlab-ci.yml

docs/ansible/index.md

docs/ansible/plugins/fluentd/index.md

docs/ansible/plugins/serverdensity/index.md

docs/ansible/roles/apache/index.md

docs/ansible/roles/borgbackup/index.md

docs/ansible/roles/composer/index.md

docs/ansible/roles/discourse/index.md

docs/ansible/roles/elastalert/index.md

docs/ansible/roles/elasticsearch/index.md

docs/ansible/roles/fail2ban/index.md

docs/ansible/roles/fluentd/index.md

docs/ansible/roles/gitlab/index.md

docs/ansible/roles/haproxy/index.md

docs/ansible/roles/heartbeat/index.md

docs/ansible/roles/jailkit/index.md

docs/ansible/roles/keycloak/index.md

docs/ansible/roles/letsencrypt/index.md

docs/ansible/roles/mysql/index.md

docs/ansible/roles/nextcloud/index.md